Heat dissipation from printed circuit boards poses a serious problem particularly in the case of high power amplifiers: integrated circuit chips for such amplifiers can for example generate in excess of 3 W each, and for some applications such as antenna arrays with several thousand chips the power consumption can be 30 kW or more. Part of the problem lies in the high level of spatial integration using multiple layers of PCBs, since it becomes difficult to arrange for a short path length between the heat generators and the heat sinks. Excessive temperatures can permanently damage the integrated circuits.
The use of a BGA facilitates assembly of a sealed integrated circuit chip, for example, onto a printed circuit, and can allow for replacement of such a chip using soldering techniques. Thermal dissipation from such a chip is conventionally done through a set of the balls of the BGA, using thermally conductive via holes through the underlying printed circuit board, through to a heat sink which may be a metallic girder and may have a fluid cooling system running through it. However, such arrangements often have an unsatisfactory rate of thermal transfer. Accordingly, the purpose of the present invention is to overcome this limitation, so as to allow satisfactory thermal dissipation from a chip with a BGA through an underlying PCB to a heat sink.